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How to Convert or Import PST File to Thunderbird?

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Published By Jamie Kaler
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Approved By Rollins Duke
Published On November 3rd, 2026
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Quick Answer: Thunderbird cannot open or import PST files directly, so you have to convert the PST file or import it through Outlook. Without Outlook using PST to Thunderbird Converter can send PST data to Thunderbird. If Outlook is installed on Windows, open the PST in Outlook and use Thunderbird’s Import from Outlook option. You can also copy the PST emails to an IMAP account such as Gmail and let Thunderbird download them.

Which Approach Should You Choose?

Choose an approach based on the PST file you have and where you want the imported email to go.

Your situation Suggested method What to know
You have a PST file and want a guided process Use a PST to Thunderbird converter Check the trial limit and test the output before converting the full archive
Outlook is installed and can access the PST file Open the PST in Outlook, then use Import from Outlook in Thunderbird Outlook must be installed. Thunderbird does not open the PST file directly
You want a free route and accept the limits Use an IMAP account as a temporary bridge It needs Outlook, uploads mail to an online account, and can be slow
You need contacts or calendar events from the PST file Use the converter to include them, or export them separately Outlook based methods may not move them in the same run

Note: This guide focuses on saved PST files. If your emails are in a configured mailbox and you want to move the whole mailbox, see the Outlook to Thunderbird guide.

What Thunderbird can and cannot import from PST?

A PST can contain more than email, but the data that reaches Thunderbird depends on the import method.

PST data What to expect in Thunderbird
Email messages The main data type covered by PST to Thunderbird methods
Attachments and inline images Check sample messages because preservation can vary based on method
Folders and subfolders Folder structure may change during conversion, verify it after import
Contacts May need a separate export and import such as CSV or VCF
Calendar events May need a separate calendar export, such as ICS
Tasks, notes, journals and other items Do not assume these will transfer, check the chosen method’s supported data types

Before importing a large archive, test a few messages with attachments and confirm that the folders and other data you need appear in the destination.

Before you convert PST to Thunderbird

A few checks can prevent problems during conversion or import:

  • Make a duplicate copy before using any approach.
  • Keep imported mail on your PC and wait for the online account to sync with the server.
  • Check messages, attachments and folder names before processing the complete mailbox data.
  • If it’s password-protected or damaged, confirm that your chosen approach supports it before its starting.
  • If Import MBOX, confirm that ImportExportTools NG supports your Thunderbird version.

Method 1. How to Convert PST to Thunderbird without Outlook?

If Outlook is not installed, or you have many PST files, MailsWare Outlook PST Converter can convert them for Thunderbird directly. It can pick up PST files from the default location or let you select them, lets you choose folders, filters by date, sender, recipients or subject, and can convert contacts and calendar along with emails. Download the software, then follow these steps.

Steps to Use PST to Thunderbird Converter

  1. Download, install and run PST to Thunderbird Importer on your PC.
    run PST to Thunderbird Converter
  2. Click on configured or let me select features based on your needs.
    select Outlook data
  3. Check on specific PST folders and tap on Next.
    select PST data
  4. Choose Thunderbird in the list of saving options.
    select Thunderbird
  5. Select filter options such as date range, subject and many more as per needed.
    select advanced settings for filter saving
  6. Click on Convert to start import PST to Thunderbird.
    click on convert to start import PST to Thunderbird
  7. Software shows you live conversion including mailbox folder name and no, of files.
    start pst to thunderbird convert
  8. The software shows you a completion message when the process gets finished.
    completion message
  9. Click on the OK button to redirect to the output data to verify converted data.
    open Thunderbird to check output data

Key features of PST to Thunderbird Converter

  • If you have several PST files, you can add them together instead of importing them one at a time.
  • You can choose only the folders you need such as Inbox, sent items or any other folders.
  • You can narrow down the emails by date, sender, recipients, cc, or subject.
  • You do not need to install Outlook as you can directly Add your PST file and select Thunderbird as the destination.
  • Keep the default Thunderbird destination for easy access, or select another location that suits your needs.

Method 2. How to Import PST to Thunderbird with Outlook?

Using this method if Outlook is installed and can access the PST file. Then, the Thunderbird Import feature allows you to read data through Outlook; it doesn’t open a PST file directly.

  1. Open Outlook and click on the file.
    click on file
  2. Now, choose open and export and select Import/Export.
    click on import/export
  3. Browse Import from another program or file and click on Next.
    choose Import from another program or file
  4. Choose Outlook data file and tap on Next.
    select outlook data file
  5. Select the PST file as you want to import and check that it do not import duplicates.
    select the pst file
  6. Choose the mailbox folder where you want to import and press on the finish button.
    select profile and mailbox folders
  7. Now, open Thunderbird and click on Menu.
    click on Menu
  8. Choose Tools and tap on Import.
    click on import
  9. Select Import from Outlook and tap on Next.
    import from outlook
  10. Choose Outlook data as you want to import and tap Next again.
    select outlook data
  11. Review selected data as you want to import and press on the Start Import button.
    start convert pst to Thunderbird

Limitations of this Method

  • Outlook installation is mandatory. Thunderbird uses Outlook to access the PST file, it cannot select and read the PST file on its own.
  • If Thunderbird or Outlook cannot find the right profile. The import may fail or show a No profile found message.
  • You first import the PST into Outlook, then import data from Outlook into Thunderbird.
  • Thunderbird import screens let you choose from the data option it detects, it doesn’t offer the same date, sender, or subject filters.
  • Compare folders and open sample emails with attachments. Move contacts or calendar items separately if they are not included in the available import process.

Optional Method: Use an IMAP Account as a Temporary Bridge

You can use an IMAP account such as Gmail to move PST emails into Thunderbird. This approach requires Outlook to upload a copy of your emails to the IMAP account, so check its storage limit first.

  1. Open Outlook and click on the file.
    click on file
  2. Tap on Add Account and configure Gmail, or any other account using IMAP.
    enter Gmail account credentials
  3. Now, Launch Outlook and click on the file again.
    click on file
  4. Choose open and export and select Import/Export.
    click on open and export
  5. Browse Import from another program or file and tap on Next button.
    import from another program or file
  6. Select Outlook data file and tap on Next button.
    select outlook data file
  7. Browse the PST file as you want to import and press Next again.
    select PST file
  8. Choose the mailbox folder where you want to import and tap the finish button.
    select mailbox folders
  9. Now, Configure the same IMAP Account in Thunderbird.
  10. Thunderbird will show all your imported emails in Thunderbird when sync properly.

This transfer can take time and folder layout may change. If a Gmail account reaches its storage limit. It may stop receiving new emails.

How to Import Large or Multiple PST Files?

  • Large PST files and multiple archives can take longer to process. Before you start, check that your computer has enough storage and keep the original files unchanged.
  • For Multiple PST files: PST to Thunderbird Converter allows you to process batch PST files. It allows you to select the complete folder of PST and can select multiple files based on user requirement.
  • For Outlook Method: Import a smaller test archive first. Confirm that its folder and messages appear in Thunderbird before continuing with the whole mailbox data.
  • For the IMAP Method: Upload and sync can take time. Check the account available storage and wait for each transfer to finish before retrying on the Thunderbird copies.
  • There is no single processing or size limit that applies to every computer archive method. It totally depends on the number of emails, attachments, available storage space and internet speed can affect the transfer.
Check Your Data After You Import PST to Thunderbird

Before relying on the imported archive, check that the messages and folders looks right:

  • Compare the folders and subfolder names with those in the PST.
  • Open messages from different dates, including Sent Items.
  • Check sender, recipient, date and subject details.
  • Open a few messages with attachments or inline images.
  • Check for missing folders and duplicate emails.
  • If you imported contacts or calendar events separately, check those too.

Keep the original PST until you have finished checking the imported data.

Fix Common PST to Thunderbird Import Errors
  • Thunderbird says “no Profile found” Error: Thunderbird uses Outlook to access data during import. Open Outlook and check that your profile is loading completely and PST is visible there, then close and relaunch both Thunderbird and Outlook and try Import again. If Thunderbird still cannot detect Outlook, use PST to Thunderbird Converter approach for hassle-free import process.
    Outlook cannot open the PST file: Work from a copy. If you suspect damage, close Outlook, run PST Recovery Tool on the copy, then open it again.
  • Some folders or messages are missing: Confirm that PST opens in Outlook and that you select folders as you want to transfer. After importing, check the folder list and compare a few messages from different dates including Sent items.
  • The import seems stuck: Large archives can take time. Make sure your computer has enough storage and let the import finish before closing either program. It repeatedly stops, trying to import small groups of data.
Frequently Asked Questions

Can Thunderbird open PST files directly?

No, Thunderbird cannot read PST files on its own. Use a PST converter, or open the PST in Outlook and use Thunderbird’s Import from Outlook option.

Can Thunderbird open an OST file directly?

No, Thunderbird cannot open an OST file directly, so you’ll need to convert OST to Thunderbird to easily access it in Thunderbird.

Is Thunderbird still supported in 2026?

Yes, Thunderbird continues to receive updates, you can check the official release notes of Thunderbird to know the latest version.

Is there a free way to import PST to Thunderbird?

Yes, The Outlook method and the IMAP bridge are free, but both need Outlook installed and have the limits described above.

Conclusion

As we already know PST to Thunderbird conversion is not directly possible. So, we have described both PST to Thunderbird Converter or using Outlook. So, choose a method that best fits with your needs. Verify the resultant folder and messages after importing and keep the original PST until you’re sure everything has been transferred successfully. For moving a configured mailbox see our Outlook to Thunderbird migration guide.

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